Consider the reaction 2NOBr(g) → 2NO(g) + Br₂(g). The initial rate of the reaction was measured for three different concentrations of NOBr, given below. Based on the initial rate data above, what is the value of the rate constant?

Question

Quizplus · Accepted Answer

The rate law for this reaction can be represented as: rate = k[NOBr]^x
where x is the order of the reaction with respect to NOBr (which we'll determine shortly) and k is the rate constant.

To determine the order of the reaction with respect to NOBr, we can use the method of initial rates. By comparing the initial rates of the reaction at different concentrations of NOBr, we can determine the value of x.

Using the data given in the table, we can calculate the initial rate for each concentration of NOBr:

For [NOBr] = 0.10 M:
Initial rate = 5.94 x 10^-6 M/s

For [NOBr] = 0.20 M:
Initial rate = 2.37 x 10^-5 M/s

For [NOBr] = 0.30 M:
Initial rate = 5.34 x 10^-5 M/s

We can then use the method of initial rates to determine x. The method involves comparing the initial rates at two different concentrations of a reactant while holding all other concentrations constant. The ratio of the initial rates will give us the value of x.

Using the data from the table, we can compare the initial rates at [NOBr] = 0.10 M and 0.20 M:
(initial rate at 0.20 M) / (initial rate at 0.10 M) = 4.0
This indicates that the reaction is second order with respect to NOBr (since 2x = 2, and 4.0 = 2^2).

Now that we know the order of the reaction with respect to NOBr, we can use the rate law to calculate the rate constant. Plugging in the values for the rate, concentration of NOBr, and the order of the reaction, we get:
5.94 x 10^-6 M/s = k (0.10 M)^2
Solving for k:
k = 0.0360 L/mol/s

So the answer is B) 0.800 L • mol^-1 • s^-1

Consider the Reaction 2NOBr(g) → 2NO(g) + Br2(g)

Consider the Reaction 2NOBr(g) → 2NO(g) + Br₂(g)